JPH07336562A - Television receiver - Google Patents

Abstract

PURPOSE:To eliminate the effect of a disturbing signal on an LD signal or the like by generating a 2nd coefficient used to limit an equalization range in addition to a coefficient corresponding to a usual equalization range with respect to coefficients for a VIT signal waveform equalization filter and using the coefficients. CONSTITUTION:A VITS extract circuit 3 extracts an equalization reference signal VITS multiplexed on a signal for a vertical blanking period from a MUSE signal via an A/D converter 1. A CPU 4 provides the output of correction coefficient to a transversal filter 2 so as to make the pulse waveform closer to an ideal waveform stored in advance. A VIT signal extracted from the MUSE signal subjected to correction by an adder 7 at the VITS circuit 3 is fed back to the CPU 4. The CPU 4 stores a standard 1st correction coefficient to a 1st memory 8 and stores a 2nd correction coefficient to a 2nd memory 9 so as to reduce the number of taps of an equalization filter. The 2nd correction coefficient is selected for, e.g. an LD signal.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a television receiver provided with a waveform equalization processing circuit for removing transmission distortion of a video signal.

[0002]

2. Description of the Related Art A high-definition television displays a fine image on a wide screen of a large screen, and seeks a new appeal such as power and presence that cannot be obtained by current television broadcasting. . For example, "high-definition" which is one of the high definition television systems
Is proposed by the Japan Broadcasting Corporation (NHK). While the current standard television system has 525 scanning lines and an aspect ratio of 4: 3, scanning lines 1125
The book has an aspect ratio of 16: 9 and has about 5 times the amount of information. In order to transmit such a signal having a large amount of information, many channels are required in the conventional terrestrial frequency band, and therefore transmission using a satellite is effective. Further, even in satellite broadcasting, a considerable band compression technique is required for transmission within the current band of one channel, and one of them is a technique called MUSE system.

What is MUSE? Multiple Sub-
Nyquist-Sampling Encoding, which is an abbreviation for sub-Nyquist sampling as the name implies, reduces the amount of information sent in one field and transmits information for one screen in four fields. Although it is a system using digital technology, the transmission is performed by analog transmission, which is called sample value analog transmission.

The basis of sampled value analog transmission is that the sampled values D / A converted by the modulator are accurately sampled without interference with each other by the A / D conversion of the demodulator. As a condition that interference between sample values does not occur,
It is known that the frequency characteristic of the transmission line should be point-symmetrical at the position of half the sampling frequency, and the group delay characteristic should be uniform within the band. I am calling.

Depending on the state of the transmission path, this cosine roll-off characteristic may not be satisfied, and in that case, waveform interference between sample values occurs and appears as ringing interference on the screen. Therefore, when the condition of the transmission line is very bad, a waveform equalizer that equalizes the transmission line may be used.

A method of equalizing the transmission line on the receiving side will be briefly described by taking the MUSE method as an example. FIG. 7 is a system diagram of transmission line equalization on the receiving side. In FIG. 7, 1 is an A / D converter, 2 is a transversal filter, 3 is V
The ITS extraction circuit, 4 is a CPU, 5 is a coefficient memory, 6 is a delay circuit, and 7 is an adder. It is necessary to multiplex the reference signal with the signal in order to perform the transmission line equalization accurately. MUSE
In the signal, an impulse waveform called a VIT signal (VITS) is multiplexed in the vertical blanking period. In the MUSE signal demodulator, the input MUSE signal is converted into a digital signal by the A / D converter 1, and then the VITS extraction circuit 3 extracts this VIT signal from the MUSE signal. And the extracted VIT
The CPU 4 compares the signal with the ideal pulse waveform, writes a coefficient for bringing the difference close to zero into the coefficient memory 5, and feeds it back as a coefficient of the transversal filter 2. The output of the transversal filter 2 is added as a correction signal to the input signal whose time is adjusted by the delay circuit 6 by the adder. With such a loop VIT
The distortion of the waveform is eliminated by gradually changing the coefficient of the transversal filter so that the difference between the signal and the ideal pulse waveform approaches zero.

The above-mentioned function of waveform equalization is not essential as a receiving device, but considering the usage form such as shared receiving equipment and cable transmission in an apartment house, the cosine roll-off characteristic in the transmission line can be always ensured. This is not necessarily the case, so it is a must-have feature for ensuring good image quality.

[0008]

As a television signal, in addition to a broadcast wave reception signal, a cable transmission (hereinafter referred to as C
There are package media such as ATV), VTR, and laser disk (hereinafter LD). Among them, it is known that the MUSE type LD has the following problems.

When the frequency spectrum of the output MUSE signal of the MUSE type LD is examined, noise may be present in the vicinity of 2.3 MHz. This noise is a disturbing component due to the pilot signal and causes a malfunction of waveform equalization. That is, since the waveform equalization processing is performed by comparing the VIT signal multiplexed in the MUSE signal with the ideal pulse waveform as described above, when a distortion component is present near the VIT signal, it is referred to as transmission distortion. Equalization processing is performed without regard. Since this is not the original transmission distortion, it has an adverse effect on the video signal, which may rather cause waveform distortion such as ringing.

It is an object of the present invention to prevent the waveform equalization processing circuit from malfunctioning due to an interfering signal superimposed on the signal of the LD and increasing the waveform distortion.

[0011]

In order to solve the above problems, a television receiver according to the present invention has a filter for receiving a television signal as an input and convolving the input signal with a predetermined coefficient value, and superimposing the filter on the television signal. A reference signal extraction circuit for extracting the generated first reference signal, and a deviation between the first reference signal extracted by the reference signal extraction circuit and a preset second reference signal is calculated and given to the filter. An arithmetic circuit for calculating the first coefficient value and the second coefficient value; and first and second coefficient memories for storing the first and second coefficient values calculated by the arithmetic circuit, It has a configuration in which the better one of the outputs of the first and second coefficient memories is selected and used as the coefficient of the filter.

[0012]

According to the present invention, according to the above-described structure, two kinds of coefficients, that is, a normal coefficient capable of equalizing the filter coefficient of the waveform equalization processing over a wide range and a coefficient for LD having a limited equalization range, are obtained. By selecting either one, it is possible to provide a good reception environment without waveform distortion even during LD reception.

[0013]

【Example】

(Embodiment 1) A television receiver according to a first embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram of a waveform equalization processing circuit of a television receiver according to a first embodiment of the present invention. In FIG. 1, 1 is an A / D converter, 2 is a transversal filter, 3 is a VITS extraction circuit, 4 is a CPU,
6 is a delay circuit, 7 is an adder, 8 is a first coefficient memory, 9
Is a second coefficient memory, and 10 is a selection circuit. The operation of the waveform equalization circuit configured as described above will be described below.

In FIG. 1, an A / D converter 1, a transversal filter 2, a VITS extraction circuit 3, and a delay circuit 6 are provided.
Operates similarly to the conventional example. Similar to the conventional example, the CPU 4 compares the ideal pulse waveform and writes the coefficient in the coefficient memory. At this time, two types of coefficients are calculated and written in the first coefficient memory 8 and the second coefficient memory 9, respectively. The same coefficient as the conventional example is written in the first coefficient memory, but the coefficient written in the second coefficient memory is set to reduce the number of taps of the equalization filter in order to narrow the equalization range. It is known that the interference in the LD described above can be dealt with by narrowing the equalization range. Therefore, when the second coefficient memory is selected by the selection circuit 10 for the LD signal, the waveform equalization due to the interference can be suppressed. A malfunction can be prevented and a good image can be obtained.

(Second Embodiment) A television receiver according to a second embodiment of the present invention will be described below with reference to the drawings.

FIG. 2 is a block diagram of a waveform equalization processing circuit of a television receiver according to the second embodiment of the present invention. In FIG. 2, 1 is an A / D converter, 2 is a transversal filter, 3 is a VITS extraction circuit, 4 is a CPU,
6 is a delay circuit, 7 is an adder, 8 is a first coefficient memory, 9
Is a second coefficient memory, 10 is a first selection circuit, and 11 is a second selection circuit. The operation of the waveform equalization circuit configured as described above will be described below.

It is assumed that the first and second television signals are input to the second selection circuit 11. The second selection circuit 11 switches one of the first and second television signals by a switching signal. At this time, if the first selection circuit is simultaneously switched by the switching signal, the first coefficient memory is used for the first television signal and the second coefficient memory is used for the second television signal. The memory can be selected automatically. Here, if the second television signal is an LD signal and the first television signal is a television signal other than LD, the second coefficient memory 9 is automatically selected at the time of LD reception, and the waveform due to interference is generated. It is possible to obtain a good image without malfunction of equalization.

Although the selection circuit 11 has been described as having two inputs, the number of input signals may be increased if necessary. In that case, the second coefficient memory 9 may be selected only when the LD input terminal is selected.

(Third Embodiment) A television receiver according to a third embodiment of the present invention will be described below with reference to the drawings.

FIG. 3 is a block diagram of a waveform equalization processing circuit of a television receiver according to the third embodiment of the present invention. In FIG. 3, 1 is an A / D converter, 2 is a transversal filter, 3 is a VITS extraction circuit, 4 is a CPU,
6 is a delay circuit, 7 is an adder, 8 is a first coefficient memory, 9
Is a second coefficient memory, 10 is a selection circuit, and 12 is an energy diffusion signal detection circuit. The operation of the waveform equalization circuit configured as described above will be described below.

The energy diffusion signal is a low frequency triangular wave which is superimposed on the signal in order to prevent the energy from being concentrated on the frequency of the carrier wave when the radio wave is FM-transmitted by using a satellite. This triangular wave is differentiated by the clamp processing performed as the preprocessing of the A / D converter 1, and remains as a square wave in the signal. The energy diffusion signal detection circuit 12 detects this residual square wave component and detects whether or not the energy diffusion signal is superimposed on the input signal. Common signals as MUSE signals are broadcast satellites (hereinafter BS), communication satellites (CS), and LD signals. Among them, BS and CS signals have energy spread signals superimposed on them. No energy spread signal is superimposed on the MUSE signal of the LD. Therefore,
It is possible to discriminate between BS, CS and LD by the energy spread signal 12. The present embodiment is characterized in that the selection circuit 10 is switched according to this discrimination signal, and the second embodiment has a problem that the input terminal of the LD is limited, whereas the input terminal is not limited. It is possible to automatically select the second coefficient memory 9 for the LD signal.

(Embodiment 4) A television receiver according to a fourth embodiment of the present invention will be described below with reference to the drawings.

FIG. 4 is a block diagram of a waveform equalization processing circuit of a television receiver according to the fourth embodiment of the present invention. In FIG. 4, 1 is an A / D converter, 2 is a transversal filter, 3 is a VITS extraction circuit, 4 is a CPU,
6 is a delay circuit, 7 is an adder, 8 is a first coefficient memory, 9
Is a second coefficient memory, 10 is a selection circuit, and 13 is a control signal detection circuit. The operation of the waveform equalization circuit configured as described above will be described below.

The control signals are various control signals transmitted by being multiplexed with the MUSE signal, and among them, a signal for discriminating whether the signal is a standard signal or a non-standard signal is included. The standard signal is a signal broadcast by a broadcasting satellite, and all other signals are non-standard signals. That is, it is possible to easily and accurately determine whether it is the BS or not.

In the third embodiment, it is possible to discriminate between BS / CS / LD, but there are problems such as the possibility of detection error due to noise and the cost increase of the detection circuit. On the other hand, in the fourth embodiment, the control signal detection circuit 13 is MUSE
It is indispensable for signal demodulation and does not add new cost, and has the advantage that the BS can be reliably identified. Therefore, if the selection circuit 10 of the first coefficient memory 8 and the second coefficient memory 9 is switched by the standard / non-standard detection signal from the control signal detection circuit 13, the CS cannot be discriminated, but the BS cannot be identified. By automatically switching between LD and LD, it is possible to obtain a good image without malfunction of waveform equalization.

(Fifth Embodiment) A television receiver according to a fifth embodiment of the present invention will be described below with reference to the drawings.

FIG. 5 is a block diagram of a waveform equalization processing circuit of a television receiver according to the fifth embodiment of the present invention. In FIG. 5, 1 is an A / D converter, 2 is a transversal filter, 3 is a VITS extraction circuit, 4 is a CPU,
6 is a delay circuit, 7 is an adder, 8 is a first coefficient memory, 9
Is a second coefficient memory, 10 is a selection circuit, and 13 is a control signal detection circuit. The operation of the waveform equalization circuit configured as described above will be described below.

The configuration of FIG. 5 differs from that of the fourth embodiment in that the AM / FM in the control signal detection circuit 13 is used.
The detection signal is being used as a control signal for the selection circuit 10. With such a configuration, the following advantages can be obtained.

As the transmission form of the MUSE signal, BS, C
In addition to S and LD, CATV transmission can be considered. CA
Since the MUSE signal by TV transmission is modulated by the AM modulation method, the energy spread signal is not superimposed, and
It is a non-standard signal. That is, in the discrimination in the third and fourth embodiments, the LDs are in the same group, and the equalization range of waveform equalization is narrowed. Therefore, in this embodiment,
By using the AM / FM detection signal in the control signal detection circuit 13 as the control signal of the selection circuit 10, the MUSE signal of CATV is discriminated, and in the case of CATV, the coefficient memory 1 is selected to widen the equalization range. In the case of the FM signal, the second coefficient memory 9 is selected and the equalization range is narrowed so that there is no problem in the case of the LD. With the above configuration, a good image can be obtained even in CATV transmission. The combination of the fourth and fifth embodiments, that is, the logical sum of the standard / non-standard detection signal and the AM / FM detection signal is taken, and the second coefficient memory 9 is set only when the signal is a non-standard signal and an FM signal. BS if you choose
In the case of, the equalization range can be widened. If combined with the energy diffusion signal detection circuit of the third embodiment,
Further, in the case of CS, the equalization range can be widened.

(Sixth Embodiment) A television receiver according to a sixth embodiment of the present invention will be described below with reference to the drawings.

FIG. 6 is a block diagram of a waveform equalization processing circuit of a television receiver according to a sixth embodiment of the present invention. In FIG. 6, 1 is an A / D converter, 2 is a transversal filter, 3 is a VITS extraction circuit, 4 is a CPU,
6 is a delay circuit, 7 is an adder, 8 is a first coefficient memory, 9
Is a second coefficient memory, 10 is a selection circuit, and 14 is a 564 line detection circuit. The operation of the waveform equalization circuit configured as described above will be described below.

In the MUSE signal, the 564th line is an empty line to prepare for future expansion. In the MUSE LD, it is considered that information specific to the LD (for example, on-screen information) is added and output using the 564 lines. In this embodiment, 56 is set on the receiver side.
A four-line detection circuit is provided, and when the input signal is an LD signal, the selection circuit 10 is switched to select the second coefficient memory 9 when the input signal is an LD signal. With such a configuration, it is possible to most certainly recognize that the input signal is the LD signal, and only in the case of the LD, the equalization range can be narrowed and a good image free from malfunction due to interference can be obtained. it can.

[0034]

As described above, according to the present embodiment, there are two coefficient memories corresponding to two kinds of tap coefficients when the equalization range is wide and when the equalization range is narrow, and the optimum coefficient is selected according to the application. By doing so, the problem of erroneous operation of waveform equalization due to the interference of the LD can be eliminated, and a good image without waveform distortion can be obtained in any case.

[Brief description of drawings]

FIG. 1 is a block diagram of a waveform equalization processing circuit of a television receiver according to a first embodiment of the present invention.

FIG. 2 is a block diagram of a waveform equalization processing circuit of a television receiver according to a second embodiment of the present invention.

FIG. 3 is a block diagram of a waveform equalization processing circuit of a television receiver according to a third embodiment of the present invention.

FIG. 4 is a block diagram of a waveform equalization processing circuit of a television receiver according to a fourth embodiment of the present invention.

FIG. 5 is a block diagram of a waveform equalization processing circuit of a television receiver according to a fifth embodiment of the present invention.

FIG. 6 is a block diagram of a waveform equalization processing circuit of a television receiver according to a sixth embodiment of the present invention.

FIG. 7 is a block diagram of a waveform equalization processing circuit of a television receiver in a conventional example.

[Explanation of symbols]

 1 A / D converter 2 Transversal filter 3 VITS extraction circuit 4 CPU 8, 9 Coefficient memory 6 Delay circuit 7 Adder 10, 11 Selection circuit 12 Energy spread signal detection circuit 13 Control signal detection circuit 14 564 Line detection circuit

Claims (6)

[Claims] 1. A filter for convolving an input signal and a predetermined coefficient value with a television signal as an input, a reference signal extraction circuit for extracting a first reference signal superimposed on the television signal, and the reference signal extraction. An arithmetic circuit for calculating a deviation between a first reference signal extracted by a circuit and a preset second reference signal, and calculating a first coefficient value and a second coefficient value to be given to the filter; A first and second coefficient memories for storing first and second coefficient values calculated by a circuit; and a selection circuit for selecting one of the outputs of the first and second coefficient memories, A television receiver comprising a waveform equalization processing circuit that uses the output of a selection circuit as a coefficient of the filter. 2. A first selection circuit for selecting one of the first and second television signals as an input, and an input signal for receiving the television signal output from the first selection circuit as an input. A filter for convoluting a predetermined coefficient value, a reference signal extraction circuit for extracting a first reference signal superimposed on a television signal, and a first reference signal extracted by the reference signal extraction circuit are set in advance. A calculation circuit that calculates the deviation from the second reference signal and calculates the first coefficient value and the second coefficient value given to the filter, and the first and second coefficient values calculated by the calculation circuit. A first and a second coefficient memory for storing, and a second selection circuit for selecting one of the outputs of the first and second coefficient memories. The second selection circuit Television receiver comprising the waveform equalization processing circuit for a coefficient of the filter Te Rikae. 3. An energy spread signal detection circuit that receives the MUSE signal as an input and detects the presence or absence of an energy spread signal multiplexed in the MUSE signal, and a filter that receives the MUSE signal as an input and convolves a predetermined coefficient value with the input signal. , A reference signal extraction circuit for extracting the first reference signal superimposed on the MUSE signal, and a deviation between the first reference signal extracted by the reference signal extraction circuit and a preset second reference signal. An arithmetic circuit for calculating the first coefficient value and the second coefficient value given to the filter, and first and second coefficient memories for storing the first and second coefficient values calculated by the arithmetic circuit. A selection circuit that selects one of the outputs of the first and second coefficient memories, and switches the selection circuit according to the output of the energy spread signal detection circuit. Television receiver comprising the waveform equalization processing circuit for a coefficient of the filter. 4. A standard / nonstandard discriminating circuit for detecting a discriminant code of a standard / nonstandard signal from a control signal multiplexed with the MUSE signal by inputting the MUSE signal, and the M
A filter that receives a USE signal as an input and convolves a predetermined coefficient value with the input signal, a reference signal extraction circuit that extracts a first reference signal superimposed on the MUSE signal, and a first signal extracted by the reference signal extraction circuit. An arithmetic circuit for calculating a difference between the reference signal of 1 and a preset second reference signal, and calculating a first coefficient value and a second coefficient value given to the filter, and a first arithmetic circuit calculated by the arithmetic circuit. And a first and second coefficient memories for storing second coefficient values, and a selection circuit for selecting one of the outputs of the first and second coefficient memories. A television receiver comprising a waveform equalization processing circuit that switches the selection circuit according to an output to use as a coefficient of the filter. 5. An AM / FM discriminating circuit which receives an MUSE signal as an input and discriminates whether the MUSE signal is AM-modulated or FM-modulated, and convolution-processing an input signal and a predetermined coefficient value with the MUSE signal as an input. A filter, a reference signal extraction circuit for extracting the first reference signal superimposed on the MUSE signal, and a deviation between the first reference signal extracted by the reference signal extraction circuit and a preset second reference signal. An arithmetic circuit that calculates and calculates a first coefficient value and a second coefficient value to be given to the filter, and first and second coefficients that store the first and second coefficient values calculated by the arithmetic circuit. A memory and a selection circuit for selecting one of the outputs of the first and second coefficient memories, and the selection circuit is switched by the output of the AM / FM discrimination circuit. Television receiver comprising the waveform equalization processing circuit of the coefficients. 6. A 564 line detection circuit for detecting 564 lines of a MUSE signal by inputting the MUSE signal, a filter for convolving the input signal and a predetermined coefficient value with the MUSE signal as an input, and a filter superposed on the MUSE signal. A reference signal extraction circuit for extracting a first reference signal, a deviation between a first reference signal extracted by the reference signal extraction circuit and a preset second reference signal is calculated, and is given to the filter. An arithmetic circuit for calculating the coefficient value and the second coefficient value, and first and second coefficient memories for storing the first and second coefficient values calculated by the arithmetic circuit,
A selection circuit for selecting one of the outputs of the first and second coefficient memories, and a waveform equalization processing circuit for switching the selection circuit according to the output of the 564 line detection circuit and using it as a coefficient of the filter. A television receiver characterized in that